Why do I need sunglasses? How does the sun

How does the sun
damage the eyes?
Three types of rays come
from the sun:
• Visible: what you see
as color.
• Infrared: invisible but felt
as heat.
• Ultraviolet (also
called UV radiation):
invisible but often
called“sunburn rays.”
UV radiation includes
two types of rays that
normally reach the
earth, UV-A rays and
UV-B rays.
Why do I need
Sunglasses can help your eyes in two important ways.
They help filter light and they protect against the damaging
rays of the sun. According to Prevent Blindness America,
sunglasses that that reduce glare and filter 99-100%
of ultraviolet (UV) rays are essential. They should be
UV protection
does not cost
a lot of money
and does not
get in the way of
seeing clearly.
comfortable and protect your eyes without any distortion.
These invisible UV rays can damage
your eyes. Some of the damage can
happen right away and some can occur
over a lifetime of exposure. Constant
exposure to bright sunlight can damage
the cornea (the clear outer part of the
eye that allows light through to the
retina), the lens (the part of the eye
responsible for focusing), and the retina
(the innermost layer of the eye that
sends an image to the brain).
How can sunglasses protect
my eyes from UV radiation?
All types of eyewear, including
prescription and nonprescription
glasses, contact lenses and lens
implants, should absorb UV-A and
UV-B rays. UV protection does not
cost a lot of money and does not get
in the way of seeing clearly. Shop for
sunglasses that block 99% to 100%
of both types of ultraviolet rays: UV-A
and UV-B. Sunglasses should also
eliminate glare and squinting. Be
wary of labels that claim a product
blocks harmful UV without specifying
exactly what percentage of UV rays
they block.
Who is at risk for eye
problems caused by
UV rays?
Anyone who spends time in the sun
is at risk, but those who spend long
hours in the sun because of work or
sports have a higher health risk from
UV rays. So do many people who have
had cataract surgery and/or certain
retinal disorders. Some people are
more sensitive to UV rays, including
those who take certain medications,
such as tetracycline, sulfa drugs,
birth control pills, tranquilizers, and
Types of Lenses
Clip-on lenses: These are used on top
of prescription eyeglasses. They are
convenient, but may not fully cover the
lens. Together with the lens surfaces of
the regular glasses, clip-on lenses may
cause reflections. They may scratch
prescription lenses or
fall off.
Gradient lenses: Sunglasses can be
of gradient density (dark on the top,
tapering to light at the bottom) or
double gradient density (dark top and
bottom, lighter in the center). They
come in handy when sunlight comes
from overhead, or is reflected into the
eyes from below.
Quality and Safety
of Lenses
Mirrored lenses: Lenses can be
coated with a thin metallic film, which
looks like a mirror and reflects light
rays, further reducing the amount of
light that can reach the eye.
Photochromatic lenses: This type of
lens changes according to the amount
of light. They darken in bright light and
lighten in dim light. These lenses are
helpful under a wide variety of light
conditions. The amount of light, lens
thickness and temperature all affect
how dark the lenses will get. One
problem with these lenses is that they
may not change quickly enough to
adjust to new light situations.
Lenses should be inspected for flaws
such as scratches, bubbles and
distortions. Poorly made glasses will
not damage the structure of your eyes.
But flaws and distortion in the lenses
may cause your eyes to work harder.
That can result in squinting, blinking,
tearing, and even slight headaches,
nausea, and dizziness. The Food and
Drug Administration requires that all
lenses be impact resistant and made
of optical-quality glass or plastic.
These are available with or without
a corrective prescription. This does
not mean the lenses are shatterproof
or unbreakable, but that they can
withstand moderate impact.
Polarizing lenses: These lenses,
which reduce glare and “bounce-up”
reflections from flat surfaces, are useful
for driving, boating, fishing and other
activities where there is glare off the
water or the ground.
Glasses for ball sports or sports with
physical impact should be made
of polycarbonate, which is the most
shatter-resistant material widely
available today. Polycarbonate
is also the best choice for
children’s sunglasses.
Color of Lenses
Neutral gray or “smoke” lenses allow
for best color perception. Other good
choices are amber or brown tints
(which usually block more blue light),
or green. Dark lenses may be preferred
by those whose eyes are very sensitive
to light. Tints such as red, orange, blue
or purple are unsuitable because they
may interfere with color perception and
tend to let in too much light. Since all
of the colors we see are made up of
visible light, tint is not related to the
degree of UV protection provided.
800.331.2020 | PreventBlindness.org
To learn more about protecting your child’s
eyes from the sun, visit starpupils.org.